Core–Shell Nanoparticles As Building Blocks for the Bottom-Up Production of Functional Nanocomposites: PbTe–PbS Thermoelectric Properties

Abstract

The bottom-up assembly of nanocrystals provides access to a three-dimensional composition control at the nanoscale not attainable by any other technology. In particular, colloidal nanoheterostructures, with intrinsic multiphase organization, are especially appealing building blocks for the bottom-up production of nanocomposites. In the present work, we use PbTe-PbS as the model material system and thermoelectricity as the paradigmatic application to investigate the potential of the bottom-up assembly of core-shell nanoparticles to produce functional nanocomposites. With this goal in mind, a rapid, high-yield and scalable colloidal synthetic route to prepare grams of PbTe@PbS core-shell nanoparticles with unprecedented narrow size distributions and exceptional composition control is detailed. PbTe@PbS nanoparticles were used as building blocks for the bottom-up production of PbTe-PbS nanocomposites with tuned composition. In such PbTe-PbS nanocomposites, synergistic nanocrystal doping effects result in up to 10-fold higher electrical conductivities than in pure PbTe and PbS nanomaterials. At the same time, the acoustic impedance mismatch between PbTe and PbS phases and a partial phase alloying provide PbTe-PbS nanocomposites with strongly reduced thermal conductivities. As a result, record thermoelectric figures of merit (ZT) of ∼1.1 were obtained from undoped PbTe and PbS phases at 710 K. These high ZT values prove the potential of the proposed processes to produce efficient functional nanomaterials with programmable properties.

Solution-based synthesis and processing of Sn- and Bi-doped Cu3SbSe4nanocrystals, nanomaterials and ring-shaped thermoelectric generators

“…From a commercial viewpoint, facile and inexpensive solution synthesis and processing allows for a lowcost and high throughput production with high material yields. [22][23][24][25][26][27] However, two major challenges in this technology are the incorporation of controlled amounts of electronic dopants and the removal of organics. Both of them are critical to optimize transport properties within such nanomaterials.…”

Colloidal Synthesis and Thermoelectric Properties of CuFeSe2 Nanocrystals

“…The nanostructuration had shown outstanding results or embedding nanoscale precipitates [8], and at the same time, enhancements in their power factors have also been achieved [6], which include introducing a resonance level in the valence band (for example, in Tl-PbTe [9]) or synergistic nanostructuring [10]. Solution processed nanoparticles have emerged as an important opportunity to control the composition and morphology of the nanostructured TE materials at the nano- and meso-scale, and the rational engineering of multicomponent and doped nanomaterials and nanocomposites is possible due to the great control and versatility that the solution processed nanoparticles provide to the construction of highly efficient TE materials [11]. Nevertheless, this is one of the major challenges that has to be solved for colloidal nanomaterials.…”

Synthesis and Thermoelectric Properties of Noble Metal Ternary Chalcogenide Systems of Ag–Au–Se in the Forms of Alloyed Nanoparticles and Colloidal Nanoheterostructures

“…16,24,25 Just as a tiny fraction of numerous examples, type II-semiconductor heterostructures such as CdSe@CdTe multibranched NPs, metal-semiconductor hybrid systems such as Au(Pt)-CdSe nanodumbbells or Au(Pt)-Cu 2 ZnSnS 4 NPs, bimetallic core@shell Co@Cu or FePd@Pd nanostructures and narrow band gap semiconductor core-shell PbTe@PbS NPs have shown to be efficient systems for optoelectronic, catalytic and thermoelectric applications. [26][27][28][29][30][31][32][33] Furthermore, colloidal NPs can then be used as pre-engineered building blocks for constructing a nanostructured extended solid with virtually unlimited control over its compositional and morphological features. 25,34,35 The most straightforward advantage of this method resides in the fact that a sub-nanometer compositional control is achieved already in the building blocks before the formation of the final composite, guaranteeing a high homogeneity in the latter.…”